Description of the core unit. In support of the experiments described in projects 1-4, the overall function of Core B will be to facilitate the identification, quantification, and analysis of cells either in tissue sections or in suspension. The accomplish this, Core B will provide the facilities methodology and expertise for flow cytometric, histologic and immunohistologic analyses. In addition to providing analytic services, Core B will also produce a range of purified and/or conjugated antibodies. These reagents will support not only FACS and histology (all projects), but will also be utilized for in vivo blocking (all projects), in vivo and in vitro cellular histology (all projects), but will also be utilized for in vivo blocking (all projects), in vivo and in vitro cellular depletion and ELISA techniques.